3.1.1-Atomic structure Flashcards
Definition Atomic number
The number of protons in a atom.
Relative charge of: Proton Neutron Electron Relative mass of: Proton Neutron Electron
Proton. +1
Neutron. 0
Electron. -1
Proton. 1
Neutron. 1
Electron. 0
Definition of atomic mass
The number of protons and neutrons in an atom
Definition of an isotope
When atoms of an element have a different number of neutrons
The order of processes in mass spectrometry
1) Electron impact ionisation / electrospray ionisation
2) acceleration
3) ion drift
4) detection
Explain Electron impact ionisation
High energy electrons are fired from an electron gun to bombard gaseous atoms and knock of an electron it then forms an ion.
Explain electrospray ionisation
Technique for ionising molecules. Dissolved sample passes through a needle attached to a positive voltage supply. Particles gain protons forming ions.
What is the best ionisation for inorganic molecules and elements.
Electron impact ionisation
What is best ionisation for organic molecules and why?
Electrospray ionisation because it dosent fragment the molecules.
Explain acceleration
Positive ions in a mass spectrometer are accelerated by magnetic field to all have same kinetic energy.
Explain ion drift
Ions emerge from electric field and drift towards detector the m/z ratio determines their velocity.
Explain detection
Ions hit a negative plate and accept electrons and so cause a small current to flow. Current is determined by abundance of each ion.
Work out the mean atomic mass
(Mass number x
percentage)
————-
Percentage added up
Define 1st ionisation energy
Amount of energy needed to remove one mile of electrons from one mile of gaseous atoms.
Explain the trend in successive ionisation energies.
General increase in amount of energy. Increase between energy levels. Because increasing effective nuclear charge.
Show a 1st ionisation energy equation for K
K (g) –> K+ (g) + e-
Show 3rd ionisation energy for K
K2+ (g) –> K3+ (g) + e-
Show electron configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6…..
What are the two anomalies of election configuration?
Why does it make them stable ?
1s2 2s2 2p6 3s2 3p6 3d5 4s1
Have 2 half filled subshells
1s2 2s2 2p6 3s2 3p6 3d10 4s1
Have one half filled subshells
Explain hunds rule
Go into separate parts ad then when go next to each they have mutual repulsion
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First ionisation energies of elements
General trend across a period
Increases
Increasing nuclear charge
Electrons experience similar shielding
therefore increased attraction and increased 1st ionisation energy.
First ionisation energies of elements
General trend down a group
Decrease
Increase nuclear charge
Electrons experience more shielding and are further away.
Therefore less attraction and decreased 1st ionisation energy.
First ionisation energies of elements.
Group 3 less than group 2
Decrease
Electrons have entered a p orbital further away from nucleus.
First ionisation energies of elements
Group 6 less than group 5
Decrease
Electrons start to pair in p orbital = mutual repulsion therefore less attraction and less ionisation energy
